Soy and Intestinal Development: Soy Alert! Update, Winter 2004

Impaired Intestinal Development

Two studies carried out by nutrition professor Sharon Donovan at the University of Illinois show that the soy isoflavone genistein, in amounts present in commercial soy infant formula, may inhibit intestinal cell growth in babies. The first, published in the Journal of Nutrition (June 2004) was an in vitro study in which Donovan treated intestinal cells in culture with genistein in the amount present in soy infant formula and found that the cells “basically stopped proliferating.”

The second was an in vivo study using pigs, to appear in the journal Pediatric Research, February 2005. Donovan fed one group of piglets a regular cow’s milk-based formula while the other groups got the formula supplemented with genistein at the level found in soy formula. In the piglets fed genistein, the number of proliferating cells in the intestine was 50 percent lower than in the piglets fed cow’s milk formula alone. Concentrations of genistein in the piglets’ blood were similar to those of babies fed soy formula, so these data may be applicable to human infants, the researchers said. Newborn pigs are an excellent model for human infants because they have a similar metabolism and physiology. The research indicated that genistein had no effect on mature intestinal cells that were no longer proliferating, but a very profound negative effect on the developing intestinal tract.

This research provides an explanation of the many reports we receive of digestive problems in soy-fed infants.

Endocrine Disruption

Researcher Claude Hughes has headed several studies on the effects of maternal exposure to soy isoflavones on the reproductive health of the offspring. In his latest study, he found that treating pregnant rats with genistein from gestational day 14 through weaning resulted in perturbations in the uterine structure that could affect the reproductive health of female offspring. The research suggests that “soy phytoestrogen exposure during reproductive development may have long-term reproductive health consequences (Exp Biol Med (Maywood) 2004 Jan;229(1):108-17). We’ve said it before but it bears repeating: pregnant and nursing women should not consume soy.

Sickly Sperm

Lorraine Anderson, a student of medicine at Queen’s University, Belfast, Northern Ireland, has devoted several years of research to the effect of soy isoflavones on markers of reproductive health. Her most important discovery has to do with the effect of soy phytoestrogens on sperm motility (www.qub.ac.uk/cm/og/lorraineandersonrp.html). Sperm surrounded by seminal fluid containing isoflavones moves more slowly. Some samples moved so sluggishly that they would have trouble reaching and fertilizing an egg. Says Anderson, “It doesn’t matter how many sperm a man’s got; if they can’t get from A to B, then there’s little chance of reproduction.”

Thyroid Troubles

A study carried out at the Department of Pediatrics at Northwestern University Medical School looked at infants with congenital hypothyroidism (Arch Dis Child. 2004 Nov;89(11):1077). Researchers found that feeding soy formula to these infants caused a prolonged increase of thyroid stimulating hormone (TSH) compared to infants fed non-soy formula. In other words, it was much harder to normalize thyroid function in the soy-fed infants.

Toxins + Soy = Trouble

Two groups of rats were exposed to environmental toxins on days 9-16 of gestation. One group was also exposed to the soy phytoestrogen genistein. Researchers found only mild changes in the mammary glands of the rats exposed to the toxins, but pronounced changes in those who got the toxins plus the genistein. Said the researchers, “Collectively, our results reveal that postnatal exposure to pharmacological levels of genistein induces profound morphological changes in the mammary glands of female rats
. . .” (Toxicol Sci. 2004 Jan;77(1):91-100).

Sidebars

The Whole Soy Story

It’s finally here! The Whole Soy Story by Kaayla T. Daniel, PhD, looks at what the science says about the effects of soy consumption on various aspects of human health–development, fertility, thyroid function and even learning and behavior. Daniel’s conclusions are ominous and this book is a must read for parents and grandparents concerned about the health of their offspring. The book is available online at wholesoystory.com and will be in the bookstores by April, in time for National Soy Month.

The FDA has responded by allowing Solae more time, which Solae specifically requested in response to our submission. The company also requested a more watered down claim. We will again respond, urging that no claim be allowed.

This article appeared in Wise Traditions in Food, Farming and the Healing Arts, the quarterly magazine of the Weston A. Price Foundation, Winter 2004.

Reader Interactions

Member Yet?

The Weston A. Price Foundation is a tireless advocate for nutrient-dense food and is wholly member supported. Becoming a member is incredibly affordable and has valuable benefits.